An in vitro study of scarring formation mediated by human Tenon fibroblasts: Effect of Y-27632, a Rho kinase inhibitor.

Scar formation is the most common cause for failure of glaucoma filtration surgery because of increased fibroblast proliferation and activation. We have now examined the effect of Y-27632, a Rho-associated protein kinase (ROCK) inhibitor, on postsurgical scarring formation in human Tenon fibroblasts (HTFs). Collagen gel contraction assay was used to compare contractility activity of Y-27632 with several antiglaucoma drugs. Immunofluorescence and western blotting were used to examine expression of scar formation-related factors. We found that Y-27632 inhibited collagen gel contraction, as well as alpha-smooth muscle actin and vimentin expression; these were promoted by treatment with latanoprost, timolol, or transforming growth factor (TGF)-beta. To investigate the effect of Y-27632 in postsurgical scarring, we mimicked TGF-beta secretion by stimulating HTFs with TGF-beta prior to Y-27632 treatment. HTFs cultured in the presence of TGF-beta significantly increased gel contraction. In contrast, when HTFs were treated with 10 mu M Y-27632, contraction was significantly inhibited. Furthermore, Y-27632 reduced TGF-beta-induced phosphorylation of mitogen-activated protein kinase signalling. These results suggest that ROCK inhibitors may inhibit fibrosis by inhibiting transdifferentiation of Tenon fibroblasts into myofibroblasts and by inhibiting TGF-beta signalling after surgery through mitogen-activated protein kinase pathway suppression. These results implicate that ROCK inhibitors may improve outcomes after filtering surgery with a potential antiscarring effect, while latanoprost and timolol may induce fibrosis. Significance of the study Scar formation is the primary cause of failure after glaucoma filtration surgery. A ROCK inhibitor, Y-27632, has been introduced as a novel potential antiglaucoma treatment to reduce intraocular pressure. The aim of our study was to elucidate the effect of Y-27632 on scarring formation after glaucoma filtration surgery, in direct comparison with other antiglaucoma drugs. Our findings thus suggested that Y-27632 may inhibit fibrosis and improve outcome after glaucoma filtration surgery through inhibition of transdifferentiation of Tenon fibroblasts into myofibroblasts, and the TGF-beta and MAPK signalling after surgery, while latanoprost and timolol may induce fibrosis.